| Arty Club Ltd | Health & social care | 2016 |
| Arya Holdings Limited | Financial services | 2019 |
| AS Emporium Ltd | Wholesale & retail | 2026 |
| AS Engineering Holdings Limited | Financial services | 2023 |
| AS Engineering-Energy Services Limited | Professional & scientific | 2012 |
| AS Express Ltd | Transport & logistics | 2024 |
| AS Good AS IT Gets (Catering) Ltd | Extraterritorial | 2025 |
| AS Niches Limited | Information & communication | 2024 |
| Asaiah Productions Ltd | Professional & scientific | 2024 |
| ASD Dental Limited | Health & social care | 2024 |
| ASE Property Ltd | Real estate | 2023 |
| ASG Advisory Limited | Real estate | 2014 |
| ASG Property Management Limited | Real estate | 2018 |
| ASH Technologies Ltd | Information & communication | 2012 |
| Asher Faith Consultancy Ltd | Real estate | 2023 |
| Ashma ALI Limited | Hospitality | 2018 |
| Ashmead Estates Ltd | Real estate | 2026 |
| Ashton Plumbing and Heating Services Ltd | Construction | 2024 |
| Ashyz Ltd | Wholesale & retail | 2023 |
| ASI Corporation Ltd | Information & communication | 2026 |
| Asian Female Entrepreneur Collective Ltd | Administrative & support | 2019 |
| ASP Online Software Limited | Information & communication | 2002 |
| Aspell Group Ltd | Arts & recreation | 2022 |
| Aspire Body Transformation Colchester Ltd | Arts & recreation | 2025 |
| Aspire Body Transformations Ltd | Arts & recreation | 2025 |
| Assisted Reading for Children | Education | 2012 |
| Aston Down Property Management Ltd | Real estate | 2024 |
| Aston Strategic Land Ltd | Professional & scientific | 2015 |
| Astonhill Land Limited | Real estate | 2014 |
| Astonhill Management Ltd | Professional & scientific | 2013 |
| Astonhill Property Consulting Limited | Professional & scientific | 2012 |
| Astral Vehicle Damage Assessors Limited | Extraterritorial | 2014 |
| Astute Consortium Ltd | Professional & scientific | 2025 |
| ASW Timber Ltd | Wholesale & retail | 2024 |
| AT Fifty Property Ltd | Real estate | 2026 |
| AT Home With LIV Ltd | Professional & scientific | 2026 |
| AT Plumbing & Heating Installations Ltd | Construction | 2011 |
| Athena Automotive Limited | Wholesale & retail | 2026 |
| Athlete Recovery Management Ltd. | Health & social care | 2016 |
| Atlantic GRC Ltd | Administrative & support | 2015 |
| Au.Thentic Jewels Limited | Health & social care | 2021 |
| Audens & Steinbach Ltd | Administrative & support | 2017 |
| Aumonier Consulting Limited | Professional & scientific | 2022 |
| Auravisionuk Ltd | Wholesale & retail | 2026 |
| Aureon Property Holdings Ltd | Real estate | 2026 |
| Auriferous Unique Ltd | Manufacturing | 2021 |
| Aurigatech Ltd | Information & communication | 2025 |
| Aurora Solar Systems Ltd | Construction | 2022 |
| Aurumblanc&Co Trading Ltd | Manufacturing | 2025 |
| Authranic Ltd | Information & communication | 2025 |
| Auto Genetics Ltd | Wholesale & retail | 2021 |
| Auto Models Limited | Wholesale & retail | 2008 |
| Auto Pro Service LLP | | 2018 |
| Auto Shine (UK) Ltd | Other services | 2007 |
| Auto WAX Coffee Limited | Hospitality | 2018 |
| Auto WAX Works Limited | Wholesale & retail | 2016 |
| Auto-Historica Limited | Manufacturing | 2020 |
| Autocolourmatch Limited | Wholesale & retail | 2016 |
| Autofarm (1973) Limited | Wholesale & retail | 1991 |
| Autofarm Ltd | Wholesale & retail | 2011 |
| Automotive Marketing Services Limited | Financial services | 1998 |
| AV Property Group Limited | Real estate | 2022 |
| AVA House Ltd | Hospitality | 2014 |
| Aveley Homes and Developments Ltd | Construction | 2018 |
| Aveley Scaffolding Ltd | Construction | 2020 |
| Avenger Holdings Limited | Real estate | 2019 |
| Avenue Residential Management Company Limited | Households | 2007 |
| Avineon Europe Limited | Information & communication | 2002 |
| Avode Limited | Construction | 2016 |
| Avonbury Business Park Management Company Limited | Real estate | 2001 |
| Axicon Auto ID Limited | Manufacturing | 1986 |
| Axicon Innovations Limited | Professional & scientific | 1992 |
| Axicon Services Limited | Real estate | 1979 |
| Ayakam Limited | Wholesale & retail | 2023 |
| Aylesbury Driver Training Ltd | Education | 2024 |
| AYU4U Limited | Wholesale & retail | 2023 |
| Azamfirei Logistics Ltd | Transport & logistics | 2026 |
| Azin Electrical Ltd | Construction | 2024 |
| B G S Construction Services Ltd | Construction | 2024 |
| B P Investment Property Ltd | Real estate | 2022 |
| B&Kc Property Investments Limited | Real estate | 2024 |
| B&P Properties (Banbury) Limited | Professional & scientific | 1964 |
| B.Blank Limited | Professional & scientific | 2018 |
| B.H.Miller Limited | Construction | 1971 |
| B.M. General Builders Ltd | Construction | 2019 |
| B.M. Yates Developments Limited | Construction | 1988 |
| B.O.B Bar Ltd | Hospitality | 2024 |
| Baba Laal Singh Logistics Ltd | Transport & logistics | 2026 |
| Babylon Apartments Ltd | Real estate | 2017 |
| Back 2 Back Spinecare Limited | Health & social care | 2023 |
| Back to ME CIC | Health & social care | 2026 |
| Badesigns (UK) Ltd | Other services | 2014 |
| Badger & Puffling Properties Ltd | Real estate | 2023 |
| Bagnall Training & Consultancy Limited | Administrative & support | 2015 |
| Bain Developments Limited | Construction | 2015 |
| Bainton Timber Limited | Agriculture & fishing | 1997 |
| Baker Heating Services Ltd | Construction | 2022 |
| Baker Leisure Limited | Hospitality | 1989 |
| Bakerpink Developments Ltd | Construction | 2025 |
| Balaji Retail Ltd | Wholesale & retail | 2026 |